1. To investigate the biochemical role of RNA directed DNA polymerase of RNA tumor virus by using specific inhibitors of the enzyme. The immediate aims are: (a) to develop potent inhibitors of reverse transcriptase. (b) to study the specificity of the inhibitors by comparison with other normal cellular polymerase. (c) to understand the molecular events of inhibition and correlate such information with antiviral and antitumor activity. 2. To investigate the mechanism of action of viral DNA polymerase from different sources, determine differences or similarities in biochemical properties, and compare viral transcriptase with normal cellular polymerase. 3. To study interaction of 70S AMV RNA with purified AMV DNA polymerase.